Precious opals are well known for their striking color displays. The strong color effect by these natural gemstones typically originates from their unique structures formed by closely packed uniformly sized silica spheres (Sanders, 1964, Nature 204:1151-1153; Acta Crystallogr., 24:427-434). These highly organized structures (super-latices of silica spheres), with sphere sizes in range that diffracts visible light, selectivity diffract certain wavelengths of visible light and thereby produce strong, angle dependent colors corresponding to the diffracted wavelengths.
In the prior art of synthetic opals, silica spheres were first synthesized and then fractionated into fractions having a narrow particle size distribution. Thereafter, spheres with a desired range of size and uniformity were assembled into closely packed arrays by sedimentation or centrifugation. The packed arrays were finally stabilized by heating or by the use of a cement-like material to bond the spheres together.
Recently it has been discovered that materials with opal-like structures may be used as photonic band gap materials or crystals. An ideal photonic band gap crystal has the capability to manipulate light (photons) in the same way as semiconductors manipulate electrons. These crystals with complete band gaps hold the promise for future super-fast optical computing and optical communication technologies.
An object of the present invention is to provide a novel process for the production of opal-like structures and to any novel intermediate and final products produced thereby. Upon further study of the specification and appended claims, other objects and advantages of the invention will become apparent.